OSXOutputPlugin.cxx

/*
 * Copyright 2003-2016 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"
#include "OSXOutputPlugin.hxx"
#include "../OutputAPI.hxx"
#include "util/DynamicFifoBuffer.hxx"
#include "util/Error.hxx"
#include "util/Domain.hxx"
#include "thread/Mutex.hxx"
#include "thread/Cond.hxx"
#include "system/ByteOrder.hxx"
#include "Log.hxx"

#include <CoreAudio/CoreAudio.h>
#include <AudioUnit/AudioUnit.h>
#include <CoreServices/CoreServices.h>

struct OSXOutput {
	AudioOutput base;

	/* configuration settings */
	OSType component_subtype;
	/* only applicable with kAudioUnitSubType_HALOutput */
	const char *device_name;

	AudioComponentInstance au;
	AudioStreamBasicDescription asbd;
	Mutex mutex;
	Cond condition;

	DynamicFifoBuffer<uint8_t> *buffer;

	OSXOutput()
		:base(osx_output_plugin) {}
};

static constexpr Domain osx_output_domain("osx_output");

static void
osx_os_status_to_cstring(OSStatus status, char *str, size_t size) {
	CFErrorRef cferr = CFErrorCreate(nullptr, kCFErrorDomainOSStatus, status, nullptr);
	CFStringRef cfstr = CFErrorCopyDescription(cferr);
	if (!CFStringGetCString(cfstr, str, size, kCFStringEncodingUTF8)) {
		/* conversion failed, return empty string */
		*str = '\0';
	}
	if (cferr)
		CFRelease(cferr);
	if (cfstr)
		CFRelease(cfstr);
}

static bool
osx_output_test_default_device(void)
{
	/* on a Mac, this is always the default plugin, if nothing
	   else is configured */
	return true;
}

static void
osx_output_configure(OSXOutput *oo, const ConfigBlock &block)
{
	const char *device = block.GetBlockValue("device");

	if (device == nullptr || 0 == strcmp(device, "default")) {
		oo->component_subtype = kAudioUnitSubType_DefaultOutput;
		oo->device_name = nullptr;
	}
	else if (0 == strcmp(device, "system")) {
		oo->component_subtype = kAudioUnitSubType_SystemOutput;
		oo->device_name = nullptr;
	}
	else {
		oo->component_subtype = kAudioUnitSubType_HALOutput;
		/* XXX am I supposed to strdup() this? */
		oo->device_name = device;
	}
}

static AudioOutput *
osx_output_init(const ConfigBlock &block, Error &error)
{
	OSXOutput *oo = new OSXOutput();
	if (!oo->base.Configure(block, error)) {
		delete oo;
		return nullptr;
	}

	osx_output_configure(oo, block);

	return &oo->base;
}

static void
osx_output_finish(AudioOutput *ao)
{
	OSXOutput *oo = (OSXOutput *)ao;

	delete oo;
}

static bool
osx_output_set_device(OSXOutput *oo, Error &error)
{
	bool ret = true;
	OSStatus status;
	UInt32 size, numdevices;
	AudioDeviceID *deviceids = nullptr;
	AudioObjectPropertyAddress propaddr;
	CFStringRef cfname = nullptr;
	char errormsg[1024];
	char name[256];
	unsigned int i;

	if (oo->component_subtype != kAudioUnitSubType_HALOutput)
		goto done;

	/* how many audio devices are there? */
	propaddr = { kAudioHardwarePropertyDevices, kAudioObjectPropertyScopeGlobal, kAudioObjectPropertyElementMaster };
	status = AudioObjectGetPropertyDataSize(kAudioObjectSystemObject, &propaddr, 0, nullptr, &size);
	if (status != noErr) {
		osx_os_status_to_cstring(status, errormsg, sizeof(errormsg));
		error.Format(osx_output_domain, status,
			     "Unable to determine number of OS X audio devices: %s",
			     errormsg);
		ret = false;
		goto done;
	}

	/* what are the available audio device IDs? */
	numdevices = size / sizeof(AudioDeviceID);
	deviceids = new AudioDeviceID[numdevices];
	status = AudioObjectGetPropertyData(kAudioObjectSystemObject, &propaddr, 0, nullptr, &size, deviceids);
	if (status != noErr) {
		osx_os_status_to_cstring(status, errormsg, sizeof(errormsg));
		error.Format(osx_output_domain, status,
			     "Unable to determine OS X audio device IDs: %s",
			     errormsg);
		ret = false;
		goto done;
	}

	/* which audio device matches oo->device_name? */
	propaddr = { kAudioObjectPropertyName, kAudioObjectPropertyScopeGlobal, kAudioObjectPropertyElementMaster };
	size = sizeof(CFStringRef);
	for (i = 0; i < numdevices; i++) {
		status = AudioObjectGetPropertyData(deviceids[i], &propaddr, 0, nullptr, &size, &cfname);
		if (status != noErr) {
			osx_os_status_to_cstring(status, errormsg, sizeof(errormsg));
			error.Format(osx_output_domain, status,
				     "Unable to determine OS X device name "
				     "(device %u): %s",
				     (unsigned int) deviceids[i],
				     errormsg);
			ret = false;
			goto done;
		}

		if (!CFStringGetCString(cfname, name, sizeof(name), kCFStringEncodingUTF8)) {
			error.Set(osx_output_domain, "Unable to convert device name from CFStringRef to char*");
			ret = false;
			goto done;
		}

		if (strcmp(oo->device_name, name) == 0) {
			FormatDebug(osx_output_domain,
				    "found matching device: ID=%u, name=%s",
				    (unsigned)deviceids[i], name);
			break;
		}
	}
	if (i == numdevices) {
		FormatWarning(osx_output_domain,
			      "Found no audio device with name '%s' "
			      "(will use default audio device)",
			      oo->device_name);
		goto done;
	}

	status = AudioUnitSetProperty(oo->au,
				      kAudioOutputUnitProperty_CurrentDevice,
				      kAudioUnitScope_Global,
				      0,
				      &(deviceids[i]),
				      sizeof(AudioDeviceID));
	if (status != noErr) {
		osx_os_status_to_cstring(status, errormsg, sizeof(errormsg));
		error.Format(osx_output_domain, status,
			     "Unable to set OS X audio output device: %s",
			     errormsg);
		ret = false;
		goto done;
	}

	FormatDebug(osx_output_domain,
		    "set OS X audio output device ID=%u, name=%s",
		    (unsigned)deviceids[i], name);

done:
	delete[] deviceids;
	if (cfname)
		CFRelease(cfname);
	return ret;
}


/*
	This function (the 'render callback' osx_render) is called by the
	OS X audio subsystem (CoreAudio) to request audio data that will be
	played by the audio hardware. This function has hard time constraints
	so it cannot do IO (debug statements) or memory allocations.
	
	The caller (i.e. CoreAudio) requests a specific number of
	audio frames (in_number_frames) to be rendered into a
	collection of output buffers (buffer_list). Depending on the
	number of output buffers the render callback has to interleave
	or de-interleave audio data to match the layout of the output
	buffers. The intput buffer is always interleaved. In practice,
	it seems this callback always gets a single output buffer
	meaning that no de-interleaving actually takes place. For the
	sake of correctness this callback allows for de-interleaving
	anyway, and calculates the expected output layout by examining
	the output buffers.
	
	The input buffer is a DynamicFifoBuffer. When a
	DynamicFifoBuffer contains less data than we want to read from
	it there is no point in doing a second Read(). So in the case
	of insufficient audio data in the input buffer, this render
	callback will emit silence into the output buffers (memset
	zero).
*/

static OSStatus
osx_render(void *vdata,
	   gcc_unused AudioUnitRenderActionFlags *io_action_flags,
	   gcc_unused const AudioTimeStamp *in_timestamp,
	   gcc_unused UInt32 in_bus_number,
	   UInt32 in_number_frames,
	   AudioBufferList *buffer_list)
{
	AudioBuffer *output_buffer = nullptr;
	size_t output_buffer_frame_size, dest;

	OSXOutput *od = (OSXOutput *) vdata;
	DynamicFifoBuffer<uint8_t> *input_buffer = od->buffer;
	assert(input_buffer != nullptr);

	/*
		By convention when interfacing with audio hardware in CoreAudio,
		in_bus_number equals 0 for output and 1 for input. Because this is an
		audio output plugin our in_bus_number should always be 0.
	*/
	assert(in_bus_number == 0);

	unsigned int input_channel_count = od->asbd.mChannelsPerFrame;
	unsigned int output_channel_count = 0;
	for (unsigned int i = 0 ; i < buffer_list->mNumberBuffers; ++i) {
		output_buffer = &buffer_list->mBuffers[i];
		assert(output_buffer->mData != nullptr);
		output_channel_count += output_buffer->mNumberChannels;
	}
	assert(output_channel_count == input_channel_count);

	size_t input_buffer_frame_size = od->asbd.mBytesPerFrame;
	size_t sample_size = input_buffer_frame_size / input_channel_count;

	// Acquire mutex when accessing input_buffer
	od->mutex.lock();

	auto src = input_buffer->Read();

	UInt32 available_frames = src.size / input_buffer_frame_size;
	// Never write more frames than we were asked
	if (available_frames > in_number_frames)
		available_frames = in_number_frames;

	/*
		To de-interleave the data in the input buffer so that it fits in
		the output buffers we divide the input buffer frames into 'sub frames'
		that fit into the output buffers.
	*/
	size_t sub_frame_offset = 0;
	for (unsigned int i = 0 ; i < buffer_list->mNumberBuffers; ++i) {
		output_buffer = &buffer_list->mBuffers[i];
		output_buffer_frame_size = output_buffer->mNumberChannels * sample_size;
		for (UInt32 current_frame = 0; current_frame < available_frames; ++current_frame) {
				dest = (size_t) output_buffer->mData + current_frame * output_buffer_frame_size;
				memcpy(
					(void *) dest,
					src.data + current_frame * input_buffer_frame_size + sub_frame_offset,
					output_buffer_frame_size
				);
		}
		sub_frame_offset += output_buffer_frame_size;
	}

	input_buffer->Consume(available_frames * input_buffer_frame_size);

	od->condition.signal();
	od->mutex.unlock();

	if (available_frames < in_number_frames) {
		for (unsigned int i = 0 ; i < buffer_list->mNumberBuffers; ++i) {
			output_buffer = &buffer_list->mBuffers[i];
			output_buffer_frame_size = output_buffer->mNumberChannels * sample_size;
			dest = (size_t) output_buffer->mData + available_frames * output_buffer_frame_size;
			memset(
				(void *) dest,
				0,
				(in_number_frames - available_frames) * output_buffer_frame_size
			);
		}
	}

	return noErr;
}

static bool
osx_output_enable(AudioOutput *ao, Error &error)
{
	char errormsg[1024];
	OSXOutput *oo = (OSXOutput *)ao;

	AudioComponentDescription desc;
	desc.componentType = kAudioUnitType_Output;
	desc.componentSubType = oo->component_subtype;
	desc.componentManufacturer = kAudioUnitManufacturer_Apple;
	desc.componentFlags = 0;
	desc.componentFlagsMask = 0;

	AudioComponent comp = AudioComponentFindNext(nullptr, &desc);
	if (comp == 0) {
		error.Set(osx_output_domain,
			  "Error finding OS X component");
		return false;
	}

	OSStatus status = AudioComponentInstanceNew(comp, &oo->au);
	if (status != noErr) {
		osx_os_status_to_cstring(status, errormsg, sizeof(errormsg));
		error.Format(osx_output_domain, status,
			     "Unable to open OS X component: %s",
			     errormsg);
		return false;
	}

	if (!osx_output_set_device(oo, error)) {
		AudioComponentInstanceDispose(oo->au);
		return false;
	}

	AURenderCallbackStruct callback;
	callback.inputProc = osx_render;
	callback.inputProcRefCon = oo;

	status =
		AudioUnitSetProperty(oo->au,
				     kAudioUnitProperty_SetRenderCallback,
				     kAudioUnitScope_Input, 0,
				     &callback, sizeof(callback));
	if (status != noErr) {
		AudioComponentInstanceDispose(oo->au);
		error.Set(osx_output_domain, status,
			  "unable to set callback for OS X audio unit");
		return false;
	}

	return true;
}

static void
osx_output_disable(AudioOutput *ao)
{
	OSXOutput *oo = (OSXOutput *)ao;

	AudioComponentInstanceDispose(oo->au);
}

static void
osx_output_cancel(AudioOutput *ao)
{
	OSXOutput *od = (OSXOutput *)ao;

	const ScopeLock protect(od->mutex);
	od->buffer->Clear();
}

static void
osx_output_close(AudioOutput *ao)
{
	OSXOutput *od = (OSXOutput *)ao;

	AudioOutputUnitStop(od->au);
	AudioUnitUninitialize(od->au);

	delete od->buffer;
}

static bool
osx_output_open(AudioOutput *ao, AudioFormat &audio_format,
		Error &error)
{
	char errormsg[1024];
	OSXOutput *od = (OSXOutput *)ao;

	memset(&od->asbd, 0, sizeof(od->asbd));
	od->asbd.mSampleRate = audio_format.sample_rate;
	od->asbd.mFormatID = kAudioFormatLinearPCM;
	od->asbd.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger;

	switch (audio_format.format) {
	case SampleFormat::S8:
		od->asbd.mBitsPerChannel = 8;
		break;

	case SampleFormat::S16:
		od->asbd.mBitsPerChannel = 16;
		break;

	case SampleFormat::S32:
		od->asbd.mBitsPerChannel = 32;
		break;

	default:
		audio_format.format = SampleFormat::S32;
		od->asbd.mBitsPerChannel = 32;
		break;
	}

	if (IsBigEndian())
		od->asbd.mFormatFlags |= kLinearPCMFormatFlagIsBigEndian;

	od->asbd.mBytesPerPacket = audio_format.GetFrameSize();
	od->asbd.mFramesPerPacket = 1;
	od->asbd.mBytesPerFrame = od->asbd.mBytesPerPacket;
	od->asbd.mChannelsPerFrame = audio_format.channels;

	OSStatus status =
		AudioUnitSetProperty(od->au, kAudioUnitProperty_StreamFormat,
				     kAudioUnitScope_Input, 0,
				     &od->asbd,
				     sizeof(od->asbd));
	if (status != noErr) {
		error.Set(osx_output_domain, status,
			  "Unable to set format on OS X device");
		return false;
	}

	status = AudioUnitInitialize(od->au);
	if (status != noErr) {
		osx_os_status_to_cstring(status, errormsg, sizeof(errormsg));
		error.Format(osx_output_domain, status,
			     "Unable to initialize OS X audio unit: %s",
			     errormsg);
		return false;
	}

	/* create a buffer of 1s */
	od->buffer = new DynamicFifoBuffer<uint8_t>(audio_format.sample_rate *
						    audio_format.GetFrameSize());

	status = AudioOutputUnitStart(od->au);
	if (status != 0) {
		AudioUnitUninitialize(od->au);
		osx_os_status_to_cstring(status, errormsg, sizeof(errormsg));
		error.Format(osx_output_domain, status,
			     "unable to start audio output: %s",
			     errormsg);
		return false;
	}

	return true;
}

static size_t
osx_output_play(AudioOutput *ao, const void *chunk, size_t size,
		gcc_unused Error &error)
{
	OSXOutput *od = (OSXOutput *)ao;

	const ScopeLock protect(od->mutex);

	DynamicFifoBuffer<uint8_t>::Range dest;
	while (true) {
		dest = od->buffer->Write();
		if (!dest.IsEmpty())
			break;

		/* wait for some free space in the buffer */
		od->condition.wait(od->mutex);
	}

	if (size > dest.size)
		size = dest.size;

	memcpy(dest.data, chunk, size);
	od->buffer->Append(size);

	return size;
}

const struct AudioOutputPlugin osx_output_plugin = {
	"osx",
	osx_output_test_default_device,
	osx_output_init,
	osx_output_finish,
	osx_output_enable,
	osx_output_disable,
	osx_output_open,
	osx_output_close,
	nullptr,
	nullptr,
	osx_output_play,
	nullptr,
	osx_output_cancel,
	nullptr,
	nullptr,
};